Disables the FMU unit test if BUILD_SHARED_LIBS is FALSE (#4647) (#314)

* disables the FMU unit test if BUILD_SHARED_LIBS is FALSE since FMU test requires shared libs (#4647)

* adds TESTONLY argument to TRIBITS_ADD_LIBRARY in the FMU test

unit_tests/testFMU_Wrapper/CMakeLists.txt

@@ -9,6 +9,5 @@
 INCLUDE(Futility_CreateUnitTest)
 
 ADD_SUBDIRECTORY(testFMU_BouncingBall)
-
 Futility_CreateUnitTest(testFMU_Wrapper)
 

unit_tests/testFMU_Wrapper/testFMU_BouncingBall/CMakeLists.txt

@@ -10,7 +10,7 @@
 INCLUDE_DIRECTORIES(${CMAKE_CURRENT_BINARY_DIR})
 INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR})
 
-TRIBITS_ADD_LIBRARY(testFMUBouncingBall SHARED
+TRIBITS_ADD_LIBRARY(testFMUBouncingBall SHARED TESTONLY
     HEADERS
       fmu2_model.h
       fmu2_model_defines.h